Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 48,334	$ 26,705
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of intangible assets	35	39
Depreciation expense	12,246	12,756
Stock-based compensation expense-restricted stock and stock units	8,886	12,113
Excess tax benefits from stock-based compensation	(2,438)	(621)
Provision for deferred income taxes	(1,554)	(7,827)
Provision for doubtful accounts receivable	2,321	1,608
Changes in assets and liabilities:
Increase in accounts receivable	(28,518)	(38,716)
Decrease in accounts payable, accrued expenses, accrued payroll costs and retirement obligations	(37,161)	(6,220)
Increase in income taxes payable	26,070	20,360
Change in other assets, net of change in other liabilities	(5,007)	(1,245)
Net cash flows provided by operating activities	23,214	18,952
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(10,372)	(14,563)
Increase in trusts for employee benefits and retirement plans	(1,478)	(1,015)
Net cash flows used in investing activities	(11,850)	(15,578)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repurchases of common stock	(56,394)	(30,967)
Cash dividends paid	(21,016)	(20,294)
Decrease in notes payable and other indebtedness	(32)	(30)
Excess tax benefits from stock-based compensation	2,438	621
Proceeds from exercises of stock options	26,081	9,661
Net cash flows used in financing activities	(48,923)	(41,009)
Effect of exchange rate changes on cash and cash equivalents	2,676	4,328
Net decrease in cash and cash equivalents	(34,883)	(33,307)
Cash and cash equivalents at beginning of period	279,336	315,137
Cash and cash equivalents at end of period	244,453	281,830
Cash paid during the period for:
Interest	107	138
Income taxes, net of refunds	$ 7,028	$ 4,212